Ink jet printers typically utilize a variety of inks, including phase change or solid inks, which are sometimes referred to as hot melt inks. Phase change inks are solid at ambient temperatures and liquid at the elevated operating temperatures of an ink jet printing device. Phase change ink is conveniently stored, transported and introduced into an ink jet printer assembly in a solid form. Prior to printing, the ink is heated to a suitable liquid phase temperature. During printer operation, liquid phase ink is supplied to the print head at the proper temperature for ejection.
Color ink jet printers typically use at least one reservoir corresponding to each different color. Separate ink jets communicate with each reservoir for printing the various ink colors. An important consideration in the design of phase change ink jet printers is providing a substantially continuous supply of liquid ink at the ink jet print head from solid ink supply means.
Early solid ink jet printers used pellets of colored cyan, yellow, magenta and black ink that were loaded into shape coded openings. The openings fed the pellets generally vertically and downwardly by gravity into the heater assembly of the printer where they entered separate reservoirs corresponding to each color. In each reservoir the ink sticks were melted into a liquid state for jetting onto the receiving medium. Other prior art solid ink jet printers used a flexible web of hot melt ink that was incrementally unwound and advanced to a heater location, or vibratory delivery of particulate solid ink to the melt chamber.
Later more successful solid ink printers, such as the Tektronix Phaser.RTM. III, the Tektronix Phaser.RTM. 300, and the Jolt printer offered by Dataproducts Corporation, used differently shaped solid ink sticks that were either passively fed by gravity or spring loaded into a feed chute. Other ink stick loading systems have utilized a horizontal feed tray in which individual ink sticks are stored end-to-end. The ink sticks are advanced in the feed tray until they fall by gravity through an aperture into a print head reservoir.
While generally adequate for their intended purposes, the prior art solid ink supply systems have a relatively limited ink stick storage capacity and are typically mechanically complex. Additionally, phase change ink color printers are now being utilized to print on wide format (E-size) media of various types. These wide-format printers consume much larger quantities of ink per print as compared to the prior art solid ink printers for standard-sized media. Accordingly, this development has emphasized the need for a large capacity ink stick supply system that provides a substantially continuous ink flow with a minimum of operator refilling requirements and mechanical failures. To assure continuous and unrestricted delivery of ink sticks to the printer, and to reduce costly down time, it is desirable that the system include provisions to prevent the individual ink sticks from adhering to adjacent surfaces in the supply system or to one another. It is also desirable to provide a simple and efficient procedure for loading a large number of multi-colored ink sticks into the supply system. The loading procedure and the supply system should cooperate to assure that the correct ink color is provided to the appropriate print head reservoir.